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Full-Text Articles in Physical Sciences and Mathematics
Calcareous Nannofossil Biostratigraphy And Paleoecology Of The Fort Hays Limestone Of Western Kansas, Western Interior Basin (Wib), Bryan Hermosillo
Calcareous Nannofossil Biostratigraphy And Paleoecology Of The Fort Hays Limestone Of Western Kansas, Western Interior Basin (Wib), Bryan Hermosillo
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
Investigations of Upper Cretaceous hemi-pelagic sediments from the Western Interior Basin suggest that high surface water fertility caused increased production of biogenic carbonate, resulting in the deposition of limestone. We examined calcareous nannofossils from the Turonian/Coniacian Fort Hays Member of the Niobrara Formation to evaluate the correlation between nannofossil surface water fertility proxies and associated lithology. Our paleoecology results indicate that oligotrophic surface water conditions were present during limestone deposition. This stands at odds with existing depositional models for the Western Interior Seaway (WIS). Paleoecological data within the interbedded marls was artificially skewed due to the prevalence of etching caused …
Evolution Of The Cretaceous Calcareous Nannofossil Genus Eiffellithus And Its Biostratigraphic Significance, J. L. Shamrock, David K. Watkins
Evolution Of The Cretaceous Calcareous Nannofossil Genus Eiffellithus And Its Biostratigraphic Significance, J. L. Shamrock, David K. Watkins
Department of Earth and Atmospheric Sciences: Faculty Publications
The calcareous nannofossil genus Eiffellithus is an important taxon of mid- to Upper Cretaceous marine sediments in biostratigraphy and paleoceanography. The definition of species within Eiffellithus have been both broadly interpreted and variably applied by nannofossil workers. This is particularly true for the Eiffellithus eximius plexus. While the taxonomy of mid-Cretaceous Eiffellithus species has recently been well-defined, the remaining 35 m.y. history of the genus has not been closely examined. Our investigation of Cenomanian to Maastrichtian sediments from the Western Interior Seaway, Gulf of Mexico, and Western Atlantic gives rise to six new species of Eiffellithus that can be reliably …